JP6459606B2 - Valve device - Google Patents

Description

  The present invention relates to a valve device having a seal chamber in which a seal member is disposed between a housing and a shaft.

(Conventional technology)
As an example of a valve device in which a seal chamber exists between a housing and a shaft, a technique disclosed in Patent Document 1 is known.
The valve device disclosed in Patent Document 1 is an EGR valve, and a seal chamber in which a seal member is disposed is provided between a shaft and a housing.
The seal chamber and the EGR passage (an example of a fluid passage) communicate with each other via a clearance portion between the housing and the shaft.

(Problems of conventional technology)
The clearance portion of the prior art is a throttle means for suppressing the amount of exhaust gas flowing into the seal chamber, and it is desirable that the clearance portion be provided as narrow as possible. Cannot be lost.
On the other hand, since the seal chamber is a space for accommodating the seal member, there is a volume.

Since the exhaust gas pulsation is transmitted to the EGR passage, a differential pressure is generated between the EGR passage and the seal chamber due to the exhaust gas pulsation or the like, and a part of the exhaust gas flowing through the EGR passage passes through the clearance portion to the seal chamber. Inflow. Then, a part of the exhaust gas stays in the seal chamber or the clearance portion, and deposits contained in the exhaust gas adhere to and accumulate on the seal chamber or the clearance portion.
The shaft is slightly decentered by the rotational play of the bearing. For this reason, the deposit accumulated in the clearance portion is compressed by the eccentricity of the shaft every time the shaft rotates.

Further, during the operation of the engine, the clearance between the housing and the shaft is widened by a difference in linear thermal expansion coefficient by being exposed to high-temperature exhaust gas. Then, deposits further accumulate in the widened clearance portion. After that, when the engine stops and cools, the clearance portion that has spread at high temperatures is narrowed, and the deposit accumulated in the clearance portion is pressed.
Since the above operation is repeated every time the engine is operated and stopped, the deposit of the clearance portion is further strongly consolidated by repeating the operation and stop of the engine.

Thus, the deposit deposited and accumulated on the clearance portion is repeatedly pressed and hardened, thereby causing a problem that the sliding resistance of the shaft increases.
In the above description, the specific example of the prior art has been described using the EGR valve. However, the problem is not limited to the EGR valve, and deposits adhere to the clearance portion even in other valve devices such as a throttle valve. Accumulation causes the same problem as described above, which increases the sliding resistance of the shaft.

JP 2010-065729 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent an increase in the sliding resistance of the shaft caused by deposits and depositing on the clearance between the shaft and the housing. In providing equipment.

The valve device of the present invention includes low pressure generating means for reducing the pressure on the upstream side of the clearance portion, and the clearance distance between the housing and the shaft forming the clearance portion is provided in a relationship of “downstream side <upstream side”. Then, when a differential pressure is generated between the fluid passage and the seal chamber and the fluid flowing through the fluid passage flows into the seal chamber through the clearance portion, the fluid that has flowed into the seal chamber flows from the upstream side of the clearance portion to the fluid passage. Return.
By providing in this way, the fluid (exhaust gas, etc.) flowing into the seal chamber or the clearance portion can be quickly discharged from the upstream side of the clearance portion to the fluid passage without being retained in the seal chamber or the clearance portion. .

  Thereby, it is possible to prevent deposits from being deposited on the seal chamber and the clearance portion. For this reason, it is possible to prevent an increase in the sliding resistance of the shaft caused by deposits deposited on the clearance. That is, the shaft rotation performance can be maintained high over a long period of time, and the reliability of the valve device can be improved.

(Example 1) which is sectional drawing of an EGR valve | bulb. (A) It is principal part sectional drawing of an EGR valve, (b) It is sectional drawing of the orthogonal | vertical direction with respect to the axial direction in the site | part in which a clearance part is provided (Example 1). (Example 1) which is explanatory drawing of the hole shape of a shaft insertion hole. It is principal part sectional drawing of an EGR valve | bulb (Example 2).

  Hereinafter, “DETAILED DESCRIPTION OF THE INVENTION” will be described in detail.

  A specific example (example) of the present invention will be described with reference to the drawings. The following “Example” discloses a specific example, and it goes without saying that the present invention is not limited to the “Example”.

[Example 1]
Embodiment 1 will be described with reference to FIGS.
In the first embodiment, the present invention is applied to an EGR valve of an EGR device (exhaust gas recirculation device).

The EGR device is a well-known technique in which part of exhaust gas discharged from the engine is returned to the intake side of the engine as EGR gas, thereby mixing EGR gas that is non-combustible gas into a part of the intake air.
The EGR device includes at least an EGR valve that opens and closes the EGR passage 1 for returning a part of the exhaust gas flowing through the exhaust passage to the intake passage and adjusts the opening thereof. The operation of the EGR valve is controlled by a control device (ECU). Be controlled.

  The EGR valve may be used for a high-pressure EGR device that returns EGR gas to the intake passage from a high exhaust pressure generation range in the exhaust passage (the exhaust upstream side of the catalyst or the particulate filter) or a low exhaust pressure in the exhaust passage. It may be used for a low-pressure EGR device that returns EGR gas from the pressure generation range (exhaust downstream side of the catalyst or particulate filter) to the intake passage.

A specific configuration example of the EGR valve will be described with reference to FIG.
In the following description, the upper side in FIG. 1 is referred to as the upper side, and the lower side in the figure is referred to as the lower side. This up-down direction is an example when the EGR valve is mounted on a vehicle, but of course is not limited.

EGR valve is
A housing 2 in which a part of the EGR passage 1 is provided;
A valve 3 disposed inside the EGR passage 1;
A shaft 4 that rotates integrally with the valve 3;
An electric actuator 5 for rotating the shaft 4;
Is provided.

Below, the specific example of each said component is demonstrated.
The housing 2 is made of die-cast aluminum alloy or the like, and a cylinder provided on the inner wall of the EGR passage 1 formed inside the housing 2 with a member (for example, stainless steel) having excellent heat resistance and corrosion resistance. A nozzle 6 having a shape is fixedly arranged. The inner periphery of the nozzle 6 forms a part of the inner wall of the EGR passage 1 in the housing 2.

The valve 3 has a substantially disk shape, is a butterfly type that can open and close the EGR passage 1 according to the rotational position of the shaft 4 and can change the opening area of the EGR passage 1 (in the nozzle 6). The EGR amount returned to the intake passage is adjusted according to the degree.
An annular groove is formed on the outer peripheral edge of the valve 3 over the entire circumference, and a seal ring 7 that eliminates a gap between the valve 3 and the inner peripheral wall of the nozzle 6 is disposed inside the annular groove.
Unlike the first embodiment, a seal ring-less type in which a separate seal ring 7 is not used on the outer peripheral edge of the valve 3 may be used.

The shaft 4 is a cylindrical rod-like shaft provided by a member having excellent corrosion resistance (for example, stainless steel), and supports the valve 3 rotatably in the EGR passage 1. The shaft 4 of the first embodiment supports the valve 3 in a cantilever manner (not limited), and the axis of the shaft 4 is inclined with respect to the diameter direction of the valve 3.
The valve 3 is fixed to the lower end of the shaft 4, and the valve 3 rotates integrally with the shaft 4. In addition, the coupling | bonding technique of the valve | bulb 3 and the shaft 4 is not limited, For example, it couple | bonds with a welding technique, a screw | thread, etc.

  The shaft 4 is rotatably supported by two bearings 8 disposed in the housing 2 above the EGR passage 1. The bearing 8 is a rolling bearing such as a ball bearing or a roller bearing, or a sliding bearing such as a metal bearing. The bearing 8 is fixed inside a bearing receiving hole formed in the housing 2 by a coupling means such as press fitting, and has an inner circumference. The shaft 4 inserted through is supported rotatably.

  The electric actuator 5 includes an electric motor (for example, a DC motor) that generates rotational power when energized, a reduction function 9 (for example, a gear reducer) that amplifies the rotational torque of the electric motor and transmits the amplified torque to the shaft 4, and a shaft. A return spring 10 for returning 4 to an initial position (valve closing position) by a spring force, and an opening sensor 11 (for example, a non-contact rotation angle sensor) for detecting the opening of the valve 3 via the shaft 4. Composed.

  The electric motor of the electric actuator 5 is energized and controlled by the control device. The control device is a well-known electronic control unit equipped with a microcomputer, and the detected opening degree (actual opening degree of the valve 3) detected by the opening degree sensor 11 is the engine operating state (engine speed and accelerator opening degree). The electric motor is feedback-controlled so that the target opening degree is calculated according to the above.

A seal member 12 for preventing EGR gas from leaking is disposed between the shaft 4 and the housing 2.
The location of the seal member 12, the number of locations, the seal structure (for example, using a bearing with a seal function) and the like are not limited, but the seal member 12 is provided at least further below the lower bearing 8. .
A space where the seal member 12 closest to the EGR passage 1 is disposed between the shaft 4 and the housing 2 is referred to as a seal chamber α.

  That is, the EGR valve (an example of a valve device) of the first embodiment includes a housing 2 in which an EGR passage 1 (an example of a fluid passage) is provided, and a valve disposed in the EGR passage 1 as described above. 3, a shaft 4 that rotates integrally with the valve 3, and a seal member 12 that seals between the housing 2 and the shaft 4.

Further, the EGR valve includes a seal chamber α in which the seal member 12 is disposed.
In order to assemble the shaft 4 so as to be rotatable with respect to the housing 2, a clearance portion β that is a gap exists between the shaft 4 and the housing 2. For this reason, the seal chamber α communicates with the EGR passage 1 via the clearance portion β.

In the prior art, in order to prevent exhaust gas from flowing from the EGR passage 1 into the seal chamber α as much as possible, the clearance distance between the shaft 4 forming the clearance portion β and the housing 2 is set to the entire circumference around the shaft 4. And as small as possible.
However, since pulsation of the exhaust gas is transmitted to the EGR passage 1, a differential pressure is generated between the EGR passage 1 and the seal chamber α, and a part of the exhaust gas flowing through the EGR passage 1 passes through the clearance portion β to enter the seal chamber. flows into α.
As a result, deposits contained in the exhaust gas adhere and accumulate in the seal chamber α and the clearance portion β. Then, by repeating the rotation of the shaft 4 with fine eccentricity, the operation of pressing the deposit deposited and deposited on the clearance portion β is repeated. As a result, the deposit accumulated and pressed on the clearance portion β causes a problem that the sliding resistance of the shaft 4 increases.

Therefore, in the first embodiment, as shown in FIG. 2B, the clearance distance between the housing 2 forming the clearance portion β and the shaft 4 is set to the relationship of “the downstream clearance distance L1 <the upstream clearance distance L2”. Provided.
The specific numerical values of the downstream gap distance L1 and the upstream gap distance L2 are of course not limited. However, when an example of assisting understanding is disclosed, the downstream gap distance L1 is about 0.1 mm to 1 mm. The clearance distance L2 on the upstream side is about 1 mm to 4 mm.

As a specific example, in the first embodiment, the shaft 4 is provided so as not to contact the housing 2 even when the axis of the shaft 4 is shifted to the upstream side.
That is, the entire range of the clearance portion β downstream of the shaft core of the shaft 4 is provided as narrow as possible, and the entire range of the clearance portion β upstream of the shaft core of the shaft 4 is provided wider than the downstream side (FIG. 3). reference).

As means for changing the gap distance between the housing 2 and the shaft 4,
(I) Change of the hole shape of the shaft insertion hole 2a,
(Ii) change of the outer peripheral surface of the shaft 4;
(Iii) Change of both the hole shape of the shaft insertion hole 2a and the outer peripheral surface of the shaft 4,
Either of these is adopted.
Specifically, in the first embodiment, by adopting the above (i) and changing the hole shape of the shaft insertion hole 2a, the clearance distance in the clearance portion β is changed to “downstream clearance distance L1 <upstream clearance distance. L2 ".

To change the shape of the shaft insertion hole 2a,
(B) Cutting,
(B) Punching process
(C) Plastic deformation processing,
(D) Die cutting when molding the housing 2 by die casting,
Any one or a plurality of combinations are employed.
Specifically, in the first embodiment, the above (d) is adopted, and the hole shape of the shaft insertion hole 2a is provided by die-casting.

The hole shape of the shaft insertion hole 2a is not limited.
As a specific example of the hole shape, as shown in FIG.
(A) a long hole shape in which two circular arcs obtained by dividing a perfect circle into two are connected by parallel straight lines;
(B) a long hole shape in which a circular arc on the downstream side and an elliptical arc on the upstream side are combined;
(C) a deformed shape having a circular arc on the downstream side and a rectangular shape on the upstream side,
(D) a round hole shape of a perfect circle (the axis true of the shaft 4 and the axis true of the shaft insertion hole 2a are shifted),
Any of these may be used, and FIG. 2B employs the above (a).

The EGR valve includes low pressure generating means γ that reduces the pressure upstream of the clearance portion β. The low pressure generating means γ of the first embodiment is a valve 3 that closes the EGR passage 1 on the upstream side of the clearance portion β when fully closed. This valve 3 performs the function of the low pressure generating means γ by reducing the pressure upstream of the clearance portion β at least when the opening is low (specifically, in the range of a small opening to a medium opening).
Further, the downstream end of the nozzle 6 closest to the shaft 4 also serves as an auxiliary function as the low pressure generating means γ that reduces the pressure upstream of the clearance portion β.

(Effect 1 of Example 1)
Since the downstream side of the clearance part β is narrowly provided so as to obtain a throttling effect, a problem that exhaust gas flows into the seal chamber α from the downstream side of the clearance part β is suppressed.
Further, even if a part of the exhaust gas flows into the seal chamber α through the clearance portion β, the upstream side of the clearance portion β that is low in pressure is largely provided, so that the exhaust gas is supplied to the seal chamber α and the clearance portion β. Without being retained, it can be quickly discharged from the upstream side of the clearance part β to the EGR passage 1.

As a result, deposits can be prevented from depositing and depositing on the seal chamber α and the clearance portion β. For this reason, it is possible to prevent an increase in the sliding resistance of the shaft 4 caused by deposits deposited on the clearance portion β.
That is, the rotation performance of the shaft 4 can be maintained high for a long period of time, the burden on the electric actuator 5 can be suppressed for a long period of time, and the long-term reliability of the EGR valve can be increased.

(Effect 2 of Example 1)
As described above, the mounting direction of the EGR valve is not limited. However, as a preferred example, the lower end of the clearance portion β is set so that the deposit dropped by the rotation of the shaft 4 falls into the EGR passage 1 by gravity. It is desirable that the EGR valve is mounted on the vehicle so that the EGR passage 1 exists on the lower side.
As described above, by disposing the EGR passage 1 below the clearance part β, it is possible to enhance the effect of discharging the deposits that have fallen off due to the rotation of the shaft 4.

(Effect 3 of Example 1)
Although the deposit amount of the deposit in the clearance portion β can be suppressed by adopting the present invention, there is a concern that the thickness of the deposit deposited in the clearance portion β increases due to long-term use.
However, as described above (see FIG. 3), since the clearance distance in the clearance portion β is provided in the relationship of “downstream clearance distance L1 <upstream clearance distance L2”, the deposit accumulated in the clearance portion β Even if the thickness is increased, the axial resistance of the shaft 4 is shifted to the upstream side due to looseness of the bearing 8 or the like, so that an increase in the sliding resistance of the shaft 4 can be prevented.
For this reason, even if the deposit on the downstream side of the clearance portion β that is provided narrowly is compressed, the pivot performance can be maintained high over a long period of time by the shaft core of the shaft 4 escaping to the upstream side. The long-term reliability of the valve can be improved.

(Effect 4 of Example 1)
In the first embodiment, as described above, “the downstream gap distance L1 <the upstream gap distance L2” is provided by die cutting when the housing 2 is molded by die casting.
For this reason, it becomes possible to implement this invention, without causing the increase in the number of processes, and the implementation cost of this invention can be held down.

[Example 2]
Embodiment 2 will be described with reference to FIG. In addition, in this Example 2, the same code | symbol as the said Example 1 shows the same function thing.

(Feature Technology 1 of Example 2)
In the second embodiment, an inclined surface 2b (tapered surface) is provided at a location in the housing 2 that forms the boundary between the seal chamber α and the clearance portion β.
In addition, although it is desirable to provide the inclined surface 2b in the whole range of the boundary part of the seal chamber (alpha) and the clearance part (beta), it is not limited and may provide only a part of boundary part in the inclined surface 2b. And you may provide the inclined surface 2b in the multiple places of a boundary part.
The inclined surface 2b is not limited to a straight section, and may be a curved surface such as an R surface.

Thus, by providing the inclined surface 2b at the boundary between the seal chamber α and the clearance portion β, the exhaust gas that has flowed into the seal chamber α flows smoothly and quickly to the EGR passage 1 via the upstream side of the clearance portion β. The deposit can be prevented from depositing in the seal chamber α and the clearance portion β.
In addition, since a part of the deposit that is compressed by the rotation of the shaft 4 can be pushed out toward the seal chamber α along the inclined surface 2b, the deposition of the deposit in the clearance portion β can be delayed.
Furthermore, since the volume of the seal chamber α can be increased by providing the inclined surface 2b, the period until the deposit is filled in the seal chamber α can be extended.

(Feature Technology 2 of Example 2)
The housing 2 of the second embodiment is provided with a notch that shortens the axial dimension of the clearance β.
The notch is provided (not limited) at the boundary between the seal chamber α and the clearance β, and in the second embodiment, the inclined surface 2b described above functions as the notch.

Thus, by shortening the axial dimension of the clearance part β, the area in which the sliding resistance of the shaft 4 increases can be reduced even when deposits are deposited and pressed on the clearance part β. Therefore, an increase in the sliding resistance of the shaft 4 can be suppressed. That is, it is possible to maintain high rotation performance over a long period of time, and the long-term reliability of the EGR valve can be improved.
In the second embodiment, the inclined surface 2b is used as an example of the notch, but the shape of the notch is not limited to the inclined surface 2b, and may be other shapes such as a step.

  In the above embodiment, an example in which the present invention is applied to an EGR valve has been shown. However, the present invention is not limited to application to an EGR valve, but a valve device that handles exhaust gas (for example, a valve device used in a turbocharger, The present invention may be applied to a valve device used in a heat recovery device, a valve device for bypass switching of an EGR cooler, or the like.

  In the above embodiment, an example in which the present invention is applied to an EGR valve as an example of a valve device that handles exhaust gas has been shown. However, the fluid to be handled is not limited to exhaust gas, and a fluid different from exhaust gas (for example, The present invention may be applied to a valve device (for example, a throttle valve, an intake throttle valve used in a low-pressure EGR device, a tumble flow or a swirl control valve, etc.) that handles engine intake.

  In the above embodiment, an example in which the valve 3 is cantilevered by the shaft 4 has been shown. However, the present invention is applied to a double-sided valve device in which the shaft 4 extending on both sides of the valve 3 is supported by the housing 2. Also good.

  In the above embodiment, the example in which the valve 3 performs the function of the low pressure generating means γ has been shown. However, the present invention is not limited to this, and a protrusion or the like is provided on the upstream side of the clearance portion β to increase the pressure on the upstream side of the clearance portion β. Lowering is also good.

1 EGR passage (fluid passage)
2 Housing 3 Valve 4 Shaft 12 Seal member α Seal chamber β Clearance section γ Low pressure generating means

Claims (5)

A housing (2) in which a fluid passage (1) is provided, a valve (3) disposed inside the fluid passage (1), and a shaft (4) that rotates integrally with the valve (3). A sealing member (12) for sealing between the housing (2) and the shaft (4),
A valve device in which a seal chamber (α) in which the seal member (12) is disposed communicates with the fluid passage (1) via a clearance portion (β) between the housing (2) and the shaft (4). In
This valve device comprises low pressure generating means (γ) for reducing the pressure on the upstream side of the clearance portion (β),
The clearance distance between the housing (2) and the shaft (4) forming the clearance (β) is small on the downstream side of the fluid passage (1) and large on the upstream side ,
When a differential pressure is generated between the fluid passage (1) and the seal chamber (α), and the fluid flowing through the fluid passage (1) flows into the seal chamber (α) through the clearance portion (β). The valve device is characterized in that the fluid flowing into the seal chamber (α) returns to the fluid passage (1) from the upstream side of the clearance portion (β) . The valve device according to claim 1,
The valve (3) is a butterfly valve that closes the fluid passage (1) on the upstream side of the clearance (β) when fully closed;
The valve device (3) serves to function as the low-pressure generating means (γ) by reducing the pressure upstream of the clearance portion (β) at least when the opening degree is low. The valve device according to claim 1 or 2,
The valve device, wherein the housing (2) includes an inclined surface (2b) at a boundary portion between the seal chamber (α) and the clearance portion (β). The valve device according to at least one of claims 1 to 3,
When the direction in which the axis of the shaft (4) extends is the axial direction,
The said housing (2) is provided with the notch part (2b) which shortens the axial direction dimension of the said clearance part ((beta)), The valve apparatus characterized by the above-mentioned. In the valve apparatus as described in any one of Claims 1-4,
The fluid passage (1) is an EGR passage (1) for returning a part of engine exhaust gas as EGR gas to the intake passage,
The valve device is an EGR valve used in an EGR device.

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